Plotting 1/x correctly
50 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
Lasse Sivertsen
il 26 Mag 2015
Risposto: Titus Edelhofer
il 26 Mag 2015
I'm trying to plot a simple function, 1/x. However it does not seem to work as intended. I define a linspace for my variable x and then use the plot() function.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/150555/image.png)
As seen in the picture, for X=3, Y= 4.95. How is this possible? For X=3, Y should be equal to 0.33?
Is there something I'm missing causing the function to break the laws of mathematics? Changing the linspace size, or simply step size results in large differences as well.
0 Commenti
Risposta accettata
Thorsten
il 26 Mag 2015
Modificato: Thorsten
il 26 Mag 2015
Because you have not specified the x values in your plot, they run from 1 to the numel(s). So X is not an absolute value but the index into your x, defined as
x = linspace(0, 10, 100);
Then
x(3) = 0.2020
so y = 1/x = 4.95.
To get the right values, use
plot(x, 1./x)
0 Commenti
Più risposte (2)
Jos (10584)
il 26 Mag 2015
Your plotting values against their index. And indeed, since x(3) is not equal to 3, but 0.2020, y(3) is not 1/3. You can use plot(x,1/.x)
Try this:
x = linspace(0,10,100) ;
y = 1./x ;
plot(x, y)
idx = 3, x(idx), y(idx)
0 Commenti
Titus Edelhofer
il 26 Mag 2015
Adding to Thorsten's answer: you need to put x on the x axis while plotting:
plot(x, 1./x);
Titus
0 Commenti
Vedere anche
Categorie
Scopri di più su Annotations in Help Center e File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!